Disclosed are methods for repelling blood-sucking and biting insects, ticks and mites involving treating an object or area with a blood-sucking and biting insects, ticks and mites repelling effective amount of at least one compound selected from
and mixtures thereof; where R is H, C1 to C10 alkyl (preferably C1-C5, more preferably C1-C3), or C1 to C10 alkenyl (preferably C1-C5, more preferably C1-C3); and optionally a carrier. Also disclosed are compositions containing at least one compound selected from
and mixtures thereof, where R is H, C1 to C10 alkyl (preferably C1-C5, more preferably C1-C3), C1 to C10 alkenyl (preferably C1-C5, more preferably C1-C3), and optionally a carrier.
Repellent substances generally cause insects to be driven away from, or to reject, otherwise insect-acceptable food sources or habitats. About 85% of insect repellent sales in the United States are for insect repellents containing N,N-diethyl-m-toluamide (DEET) as their primary active ingredient. Although DEET is an effective repellent, it possesses an unpleasant odor and imparts a greasy feeling to the skin. In addition, concerns have been raised as to its safety, particularly when applied to children (Briassoulis, G., et al., Human & Experimental Toxicology, 20(1): 8-14 (2001)). Another disadvantage of DEET is that it dissolves or mars many plastics and painted surfaces.
Because of the above limitations, DEET-free products with repellent activity are being sought. New candidate repellents should possess a desirable balance of properties and will preferably reach or exceed the positive properties of DEET, and/or not suffer from its negative properties (Hollon, T., The Scientist, Jun. 16, 2003, pages 25-26). Potential substitutes for DEET should desirably then exhibit a combination of excellent repellency, high residual activity, and low toxicity to humans (or pets) and the environment. Any candidate to replace DEET should exhibit repellency to a wide variety of insects considered noxious by humans, including, but not limited to, biting insects, wood-boring insects, noxious insects, household pests, and the like. In addition, there is increasing demand for repellent compounds that can be obtained from, or synthesized from, natural plant materials and that are pleasant to use.
Many plant species produce essential oils (aromatic oils) which are used as natural sources of insect repellent and fragrant chemicals (Hay, R. K. M., and K. P. Svoboda, Botany, In Volatile Oil Crops: Their biology, chemistry and production, R. K. M. Hay and P. G. Waterman (eds.), Longman Group UK Limited (1993)). Plants of the genus Nepeta (catmints) produce an essential oil that is very rich in a class of mono terpenoid compounds known as iridoids (Inouye, H., Methods in Plant Biochemistry, 7:99-143 (1991)), more specifically the cyclopentanoid nepetalactones (Clark, L. J., et al., The Plant Journal, 11: 1387-1393 (1997)) and derivatives. Studies of the repellency of catnip oil (predominantly nepetalactone) showed that it was repellent towards a number of insect species (e.g., mosquitoes, cockroaches, ants) on short-term exposure but not to a number of other species (e.g., agriculture pests such as stink bugs, beetles, etc.) (Eisner, T., Science, 146: 1318-1320 (1964)). Similarly plants in the cat thyme family contain volatile iridoid monoterpenes and have shown a similar spectrum of semiochemistry (Tucker and Tucker, Economic Botany, 42, 214-231 (1988)).
U.S. Pat. No. 4,663,346 discloses insect repellants containing bicyclic iridoid lactones (e.g., iridomyrmecin). U.S. Pat. No. 4,869,896 discloses use of these bicyclic iridoid lactone compositions in potentiated insect repellent mixtures with DEET. U.S. Pat. No. 6,524,605 discloses insect repellents containing nepetalactones derived from the catmint plant N. cataria. U.S. Patent Application 2004/0127553 discloses that dihydronepetalactones have been identified as an effective insect repellent compound. U.S. Pat. No. 7,067,678 discloses that 3-substituted dihydronepetalactones are insect repellants. However, there continues to be a need for additional commercially and economically viable better alternatives to DEET with efficacy, safety profile and less vapor pressure.